feat(workspace): split menus start AI tools; drop the Tools menu

A pane's split right/down menus offered only New terminal. They now list
the same AI tools as the tab bar's + menu (newTabTools/newTabBody,
shared from ConsoleTabs), started bare in the first free slot on that
side of the pane.

The tab bar's Tools menu is gone: its readme run hit 409 ERUNLIVE
whenever slot 0 was live (always, in the session view) and depended on
a personal skill; MCP sync and the dev-sync check served the dormant
ship-feature-lane pipeline. The sidebar row menu's readme item goes too.
The routes stay, reached by `agenthub lanes mcp sync` and
`agenthub lanes sync-base`.

Also: the home's Memory header and file tabs no longer shrink (a long
file squeezed the tab row and clipped it).

client/src/components/lanes/__tests__/AddLaneModal.test.tsx

@@ -589,9 +589,8 @@ describe("AddLaneModal — folder browse", () => {
 });
 
 describe("AddLaneModal — create/update readme", () => {
-  it("no longer offers it here — it moved to the lane's Tools menu", async () => {
-    // Creating a lane and writing its docs are separate decisions, and the
-    // second one is worth re-running later; see LaneToolsMenu.
+  it("is not offered here", async () => {
+    // Creating a lane and writing its docs are separate decisions.
     renderModal();
     const user = userEvent.setup();
     await user.click(screen.getByRole("button", { name: "Repo" }));